This document discusses types of HVAC systems and components. It describes two main types of air conditioning units: direct expansion (DX) units that use refrigerant to cool air directly, and chilled water (CH) units that use chilled water running through coils to cool air. It then provides details on different DX unit configurations like package units, ducted split units, and mini-split units. The document also discusses chilled water air conditioning components like air cooled and water cooled chillers. It covers other HVAC components such as air handling units, compressors, condensers, and fans.

1. Heating, Ventilation and Air
Conditioning (HVAC) Systems
Module (1.1)
Types of A/C Units and System
Instructor
Eng. Juma Yousef Juma-Getco

2. HVAC SYSTEM
OPERATION AND TYPES

3. Types of A/C Units and System
according to Air Cooling Methods
2) CH-Chilled Water 1) DX-Direct Expansion

4. Types of A/C Units and System
according to Air Cooling Methods
1) DX-Direct Expansion2) CH-Chilled Water
Interior-‫الداخلى‬ ‫المحيط‬
(COLD AIR)
‫الوحدة‬
‫الداخلية‬
Indoor
Unit
Freon
Cooling
Water
CH. W.
Cool Air
Freon
Cooling
Air

5. DX Units types

6. ‫للهواء‬ ‫مباشر‬ ‫تكييف‬DX-Direct Expansion

7. DX-Components

8. DX-Package Unit DX-Ducted Split

9. ‫وحدة‬
‫منفصلة‬
*To be fixed in lower floors at multi
story villas.
*multi story buildings.
*Occupied less outer space &
reduce ducting.
*Can connect more than one room.
*Give more flexibility for decoration.
*Cheaper than package units.
*Difficult to replacing the future if
needed.
*Efficiency Ratio: 1.8 kw per ton in
average.
*‫المناز‬ ‫من‬ ‫السفلي‬ ‫األدوار‬ ‫في‬ ‫تركب‬‫ل‬
‫األدوار‬ ‫المتعددة‬.
*‫األدوار‬ ‫متعددة‬ ‫السكنية‬ ‫العمارات‬.
*‫اقل‬ ‫خارجية‬ ‫مساحة‬ ‫تشغل‬.
*‫ومساحة‬ ‫الهواء‬ ‫مجاري‬ ‫في‬ ‫توفر‬
‫اإلشغال‬.
*‫غرفة‬ ‫من‬ ‫أكثر‬ ‫ربط‬ ‫يمكنها‬
*‫الديكو‬ ‫تصميم‬ ‫في‬ ‫التحكم‬ ‫تتيح‬‫رات‬.
*‫المدمجة‬ ‫من‬ ‫وأرخص‬ ‫التكلفة‬ ‫في‬ ‫أقل‬.
*‫المستقب‬ ‫في‬ ‫االستبدال‬ ‫عند‬ ‫أصعب‬‫ل‬.
*‫التبريد‬ ‫كفاءة‬:1,8‫طن‬ ‫لكل‬ ‫كيلوات‬
‫المعدل‬ ‫فى‬ ‫تبريد‬.
Features
‫المميزات‬
Ducted
Split Unit

10. Ducted Split Unit

11. ‫مدمجة‬ ‫وحدة‬
Package Unit
* To be fixed at villas of one floor.
*To be fixed at higher floor in
multi story villa.
*Easier to maintain &
repair
*Less inconvenience.
*Easier to replace in the future.
*Efficiency Ratio: 1.6 kw per ton
in average
*‫الدور‬ ‫ذات‬ ‫المنازل‬ ‫في‬ ‫تركب‬
‫الواحد‬
*‫للمنز‬ ‫العلوي‬ ‫الدور‬ ‫في‬ ‫تركب‬‫ل‬
‫الدورين‬ ‫ذات‬
*‫اإلصال‬ ‫وعند‬ ‫الصيانة‬ ‫في‬ ‫أسهل‬‫ح‬
*‫البيت‬ ‫ألهل‬ ‫إزعاجا‬ ‫أقل‬.
*‫المست‬ ‫في‬ ‫االستبدال‬ ‫عند‬ ‫أسهل‬‫قبل‬.
*‫التبريد‬ ‫كفاءة‬:1,6‫لكل‬ ‫كيلوات‬
‫المعدل‬ ‫فى‬ ‫تبريد‬ ‫طن‬
Features
‫المميزات‬

12. PKG in Duty

13. ‫منفصلة‬ ‫وحدة‬
Mini-Split Unit
*To be fixed in lower floors at multi
story buildings.
*Occupied less outer space & reduce
ducting.
*Can't connect more than one room.
*Give more flexibility for decoration.
*Cheaper than package units.
*Easiest to replace in the future if
needed.
*Efficiency Ratio: 2.0 kw per ton in
average.
*‫المناز‬ ‫من‬ ‫السفلي‬ ‫األدوار‬ ‫في‬ ‫تركب‬‫ل‬
‫األدوار‬ ‫المتعددة‬.
*‫أقل‬ ‫خارجية‬ ‫مساحة‬ ‫تشغل‬.
*‫ومساحة‬ ‫الهواء‬ ‫مجاري‬ ‫في‬ ‫توفر‬
‫اإلشغال‬.
*‫معا‬ ‫غرفة‬ ‫من‬ ‫أكثر‬ ‫ربط‬ ‫يمكنها‬ ‫ال‬.
*‫الديكور‬ ‫تصميم‬ ‫في‬ ‫الحرية‬ ‫تتيح‬‫ات‬.
*‫والمنفص‬ ‫المدمجة‬ ‫من‬ ‫التكلفة‬ ‫في‬ ‫أقل‬‫لة‬.
*‫األ‬‫المستقب‬ ‫في‬ ‫االستبدال‬ ‫عند‬ ‫سهل‬‫ل‬.
*‫التبريد‬ ‫كفاءة‬:2,00‫كيلوات‬/‫طن‬
‫المعدل‬ ‫فى‬ ‫تبريد‬
Features ‫المميزات‬

14. Split Unit Working

15. ‫منفصلة‬ ‫وحدة‬
Mini-Split Unit
*Stylish Decorative Unit..
*Occupied less inside space & reduce
ducting.
*Can't connect more than one room.
*Give more flexibility for decoration.
*Cheaper than package units.
*Easiest to install & replace in the
future if needed.
*Drain Pump for Condensate Water
*Efficiency Ratio: 2.0 kw per ton in
average.
*‫جميلة‬ ‫ديكورية‬ ‫وحدة‬.
*‫أقل‬ ‫داخلية‬ ‫مساحة‬ ‫تشغل‬.
*‫ومساحة‬ ‫الهواء‬ ‫مجاري‬ ‫في‬ ‫توفر‬
‫اإلشغال‬.
*‫الديكور‬ ‫تصميم‬ ‫في‬ ‫الحرية‬ ‫تتيح‬‫ات‬.
*‫والمنفص‬ ‫المدمجة‬ ‫من‬ ‫التكلفة‬ ‫في‬ ‫أقل‬‫لة‬.
•‫األ‬‫عند‬ ‫سهل‬‫و‬ ‫التركيب‬‫في‬ ‫االستبدال‬
‫المستقبل‬.
•‫التكثيف‬ ‫مياه‬ ‫لدفع‬ ‫مضخة‬.
*‫التبريد‬ ‫كفاءة‬:2,00‫كيلوات‬/‫طن‬
‫المعدل‬ ‫فى‬ ‫تبريد‬
Features
‫المميزات‬

16. ‫المنفصلة‬ ‫الوحدات‬ ‫أنواع‬
Types of Mini-Splits

17. Decorative Units provide Flexibility, fast to
install, cheaper and easy to replace

18. ‫متعدد‬ ‫منفصلة‬ ‫وحدة‬‫ة‬
Multi-Split Unit
*Can be fixed various
building types.
*Flexible operation
matches space usage.
*Occupied less outer
space.
*Cond. Unit can be
fixed as far as 50 mtr.
*Optimum operation
with higher efficiency.
*‫في‬ ‫للتركيب‬ ‫تصلح‬‫كافة‬
‫المنازل‬.
*‫تشغيلها‬ ‫في‬ ‫تتالءم‬‫مع‬
‫مرافق‬ ‫إشغال‬ ‫طبيعة‬
‫المنزل‬.
*‫خارجية‬ ‫مساحة‬ ‫تشغل‬
‫أقل‬.
*‫بعيد‬ ‫تركيبها‬ ‫يمكن‬‫عن‬ ‫ا‬
‫سطحه‬ ‫وعن‬ ‫المنزل‬.
*‫بالك‬ ‫تشغيلها‬ ‫يتميز‬‫فاءة‬
‫استهال‬ ‫وتوفير‬ ‫العالية‬‫ك‬
‫الكهرباء‬.Features ‫المميزات‬

19. VRF-Reliability

20. VRF-Flexibility

21. VRF-Components

22. Chillers types

23. Air Cooled Package Chiller‫التكييف‬ ‫لمياه‬ ‫مدمج‬ ‫مبرد‬ ‫شلير‬

24. Chiller Components

25. Air Cold Chiller

26. Water Cold Chiller

27. Industrial air conditioner-

28. Condenser types

29. Air cooled units absorb heat
from the indoor space and
rejects it to ambient air.
Condenser
compressor,
propeller fans
and controls
These are the most common
system used in residential and
light commercial applications.
PARTS
Condenser Air Cooled System

30. Chilled Water System with Air
Cooled Condenser

31. Water cooled units absorb the heat from the
indoor space and rejects that heat to water
which in turn may either reject heat via fluid
coolers or cooling towers, or dry air coolers
with adiabatic kits.
o higher coefficient of performance (COP).
o most common
o multi-storey offices, hotels, airports and
shopping complexes.
Condenser Water System – Cooling Tower

32. Chilled Water System with Water
Cooled Condenser

33. Condenser Water System
air cooled unit water cooled unit
H2O

34. Compressor types

35. Rotary Compressor ‫دوار‬ ‫ضاغط‬-

36. ‫كباس‬ ‫ترددى‬ ‫ضاغط‬-Reciprocating Comp.

37. Full Strokes

38. Sealed ‫مغلق‬- Semi-Sealed ‫نصف‬-
‫كباس‬ ‫ترددى‬ ‫ضاغط‬-Reciprocating Comp.

39. Scroll Compressor – ‫لولبي‬ ‫ضاغط‬

40. ‫الض‬ ‫طريقة‬‫خ‬–Compression Method

41. Screw Compressor – ‫برغي‬ ‫ضاغط‬

42. ‫الض‬ ‫طريقة‬‫خ‬–Compression Method

43. ‫الض‬ ‫طريقة‬‫خ‬–Compression Method

44. ‫الض‬ ‫طريقة‬‫خ‬–Compression Method

45. ‫جديدة‬ ‫ضغط‬ ‫طريقة‬New Compression Method

46. Turbo core Compressor

47. Turbo core Compressor

48. Turbo core Chiller

49. Range of Applications of Compressors
Domestic
Refrigerators
& Freezers
Automotive
Air Cond’g
Room Air
Conditioners
Unitary Air
Conditioners
& Heat Pumps
Commercial
Air Cond’g &
Refrigeration
Large Air
Conditioning
Cooling Capacity
Fractional 200 kW (50 tons)
Reciprocating
Fractional 10 kW (3 tons)
Rotary
5 kW (1.5 tons) 70 kW (20 tons)
Scroll
150 kW (40 tons) 1500 kW (400 tons)
Screw
350 kW (100 tons) and up
Centrifugal

50. 50
100101.1
0
2
4
6
8
10
12
14
16
18
WATER COOLED CHILLER DUTY
CFM/TON
DELTAH,(Btu/lb)
POSITIVE DISPLACEMENT,
ROTARY, SCROLL, RECIP, SCREW
CENTRIFUGAL
113
123
11
114
124
134
152a
134a
12
500
22
502
125
507
143a
410A
32
Application Considerations
 The
refrigerant
and
application
determine
 Flow
 Lift
 PD
Compressors
are ideally
suited for
higher lift
 Centrifugal
Compressors
have high
volumetric
flow

51. ‫الهواء‬ ‫دفع‬ ‫وحدات‬
Air Handling Units

52. FAN-COIL UNIT

53. FCU-Fan Coil Unit is the part of
Chilled Water System that deliver
cooling to independent zones.
These typically used in separate
rooms/guestroom and small offices
with limited ductwork for better air
distribution.
‫من‬ ‫هام‬ ‫جزء‬ ‫هي‬ ‫الهواء‬ ‫دفع‬ ‫وحدة‬
‫المركزى‬ ‫التكييف‬ ‫منظومة‬‫بالمياه‬
‫المبردة‬‫تخدم‬‫األغلب‬ ‫فى‬‫منطق‬‫ة‬‫م‬‫ح‬‫ددة‬
‫غرفة‬ ‫مثل‬/‫صغي‬ ‫مكتب‬ ‫أو‬ ‫فندقية‬‫ر‬,‫و‬
‫دكت‬ ‫مجارى‬ ‫عبر‬ ‫البارد‬ ‫الهواء‬ ‫ثدفع‬
‫قصيرة‬‫لت‬‫أفض‬ ‫بشكل‬ ‫الهواء‬ ‫وزع‬‫ل‬.

54. FAN COIL UNIT
• It part of an HVAC system found in residential, commercial, and
industrial buildings.
• A simple device consisting of a heating or cooling coil and fan.
• Used to control the temperature in the space where it is
installed, or serve multiple spaces.
• It is controlled either by a manual on/off switch or by
thermostat.
• Fan coil units are more economical to install than ducted or
central heating systems with air handling units.
• They can be noisy because the fan is within the same space.

55. A/C Unit is: Fan + Coil = FCU

56. Fan Coil System - Advantages
• Central equipment may be sized smaller by taking
advantage of building heating and cooling diversity.
• The system requires only piping installation which takes
up less space than all-air duct systems.
• It is usually easier to install wire and water pipes than
ducts making this a good choice for retrofit
applications.
• Unoccupied areas of the building may be isolated and
shut down, saving money.
• Zones can be individually controlled.
• Can take up to 100% outside air capability (see next slide).

57. Fan Coil Unit – FCU Components

58. DESIGN - ‫التصميم‬
• A fan coil unit may be concealed or exposed within the room or
area that it serves.
• An exposed fan coil unit may be wall mounted, freestanding or
ceiling mounted.
• It typically include an appropriate enclosure to protect and conceal
the fan coil unit itself.
• Return air grille and supply air diffuser set into that enclosure to
distribute the air.
• A concealed fan coil unit will typically be installed within an
accessible ceiling void or services zone.
• The return air grille and supply air diffuser will be ducted to and
from the fan coil unit.

59. OPERATION ‫التشغيل‬-
• The coil receives hot or cold water from a central plant, and removes heat
from or adds heat to the air through heat transfer.
• Traditionally fan coil units can contain their own internal thermostat, or
can be wired to operate with a remote thermostat.
• In most modern buildings with a Building Energy Management
System (BEMS), the control of the fan coil unit will be by a local digital
controller. equipment for adding heat to the building's water.
• Fan coil units circulate hot or cold water
through a coil in order to condition a space.
• The unit gets its hot or cold water from a
central plant, or mechanical
room containing equipment for removing
heat from the central building's closed-loop.
• The equipment used can consist of
machines used to remove heat and

60. TYPES ‫األنواع‬-
Conceal
FCU
Decorative FCU Exposed

61. Conceal
FCU
with
Duct

62. TYPES ‫األنواع‬-
Two-pipe
FCU for
Cooling Only
Four-pipe FCU
for
Cooling/Heating

63. TYPES ‫األنواع‬-
Low Static FCU
(No Duct or
Small Duct
Medium Static
FCU with
ducting
High Static FCU
with more
ducting

64. AHU
Air Handling Unit

65. AHU System - Disadvantages
• Long, big in size and expensive GI Duct.
• Taking extra space from the building.
• Relatively high noise levels (at high
output)
• Might have week return from far branch.
• High operating and maintenance
costs (for changing the filter and fan)

66. What is AHU?
• An air handler, or air handling unit (often abbreviated
to AHU), is a device used to condition and circulate air
as part of a heating, ventilating, and air-conditioning
(HVAC) system.
• An air handler is usually a large metal box containing
a blower, heating or cooling elements, filter racks or
chambers, sound attenuators, and dampers.
• Air handlers usually connect to a ductwork ventilation
system that distributes the conditioned air through the
building and returns it to the AHU.
• Sometimes AHUs discharge (supply) and admit
(return) air directly to and from the space served
………without ductwork.

67. ‫الباردة‬ ‫المياه‬
water
Air-‫الهواء‬

68. 1

69. 2

70. 3

71. 4

72. CONSTRUCTION AND MATERIALS
• The air handler is normally constructed around a framing
system with metal infill panels as required to suit the
configuration of the components
• In its simplest form the frame may be made from metal
channels or sections, with single skin metal infill panels. The
metal work is normally galvanized for long term protection.
• For outdoor units some form of weatherproof lid and
additional sealing around joints is provided.
• Larger air handlers will be manufactured from a square
section steel framing system with double skinned and insulated
infill panels.
• Such constructions reduce heat loss or heat gain from the air
handler, as well as providing acoustic attenuation. Larger air
handlers may be several meters long and are manufactured in a
sectional manner and therefore, for strength and rigidity, steel
section base rails are provided under the unit.

73. ‫الهواء‬ ‫معالجة‬ ‫وحدة‬AHU
Air Handling Unit

74. AHU Operation – ‫العمل‬ ‫نظرية‬

75. COMPONENTS
• An air handling unit; air flow is
• from the right to left in this case.
• Some AHU components shown are
• 1 – Supply duct
• 2 – Fan compartment
• 3 – Vibration isolator ('flex joint')
• 4 – Heating and/or cooling coil
• 5 – Filter compartment
• 6 – Mixed (recirculated + outside) air duct

76. • VERTICAL AHU
HORIZONTAL
AHU
CELING MOUNTED AHU
AHU classified on basis of
installation

77. VERTICAL AIR HANDLING UNITS
• designed for vertical in room
mounting
• VAHU comes with a fan and a
cabinet that can produce high profile
static pressures without occupying
the larger footprint area
FEATURES
•high performance
•cost effective small air-handling
•Suitable for spaces with less area
APPLICATION
• Classroom
• Laboratories
• Pharmaceutical
labs

78. HORIZONTAL AHU
Features:
Low cost
Reliable
Easy to use
High durability
Application
homes
offices
institutions
factories
floor mounted air handler is usually a large metal
box containing a bowler, heating or cooling
element

79. CEILING MOUNTED AHU
•Can be suspended from the ceiling and hence
require no floor space
•Noiseless units and can be placed above the
false ceiling in the conditioned area
•Units are unobtrusive giving flexibility to the
design of the interior
Features :
Cost efficient
High quality product
Easy to use
Perfect functionality
Applications :
Shopping Malls
Multiplexes
Small Offices
Ware houses

80. AHU-according to feeding Area
• single-zone Multi-zones

81. Draw through type:
fan located after
cooling coil
TYPE OF AHU DEPENDING ON LOCATION OF FAN
Blow through type:
fan located before
cooling coil

82. Draw through type:
fan located after
cooling coil
TYPE OF AHU DEPENDING ON TYPE OF FAN
Blow through type:
fan located before
cooling coil

83. Draw through type Blow through type
Lower condensation of water Higher condensation
Less air leakage More chances of air leaking
heat generated by fan
and motor added to air
downstream
of cooling coil, requiring
a colder leaving-coil
temperature to achieve
a desired supply-air
temperature
Heat generated by the fan and
motor is added to the air
upstream
of the cooling coil, allowing
for a warmer leaving-coil
temperature to achieve
a desired supply-air
temperature
TYPE OF AHU DEPENDING ON LOCATION OF FAN

84. •PACKAGED AHU
•common in smaller buildings and
commercial applications, particularly as
rooftop units.
•Packaged unit contain fans, coils, filters,
and dampers in a single casing
• casing include air conditioning
compressors, heaters such as gas
burners, electric heating coils, or heat
pump coils.
•serve single temperature zones, VAV
serving multiple terminal boxes (zones)
are available.
•FEATURES
•Compact
•lower initial costs
•DISADVANTAGES
•inefficient
•maintenance intensive

85. ADVANTAGES
• Modular construction and wide selection of air handling unit sizes
• Wide application range
• Low energy consumption
• Low risk of condensation : air tight
• Easy installation and adaptability to building condition
• Easy maintenance: hygienically friendly
DISADVANTAGES
• AHU is physically large and requires careful planning in terms of a
suitable location.
• The space required for ducting and the corresponding holes through
building fabric require careful co-ordination with builders and other
mechanical services within the room.
• Rooms with variable or moving sources of heat gain such solar gain
traversing around the room require sophisticated duct work and
controls. Zone heaters may have to be incorporated into duct
branches.

86. lifting or rigging the AHU to the
site
locate the AHU in the AHU room
preparing unit for the installation
assembling the unit
cabinet installation
fan installation
electrical installation
 coil and piping installation sheet
metal installation
final installation
controls installation
final sensor and actuator
……………………..calibration
verification
INSTALLATION PROCESS

87. Duct & Accessories

89. COMPONENTS
• Filters
• to provide clean dust-free air to the building
occupants
• It may be via simple , HEPA, electrostatic, or a
combination of techniques. Gas-phase and ultraviolet
air treatments may be employed as well.
• Filtration is typically placed first in the AHU in
order to keep all the downstream components clean.
• Depending upon the grade of filtration required,
typically filters will be arranged in two (or more)
successive banks with a coarse-grade panel filter
……..provided in front of a fine-grade bag filter.

90. • Air handlers may need to provide heating, cooling, or both to
change the supply air temperature, and humidity level depending on
the location and the application.
• Such conditioning is provided by heat exchanger coil(s) within the
AHU air stream, such coils may be direct or indirect in relation to
the medium providing the heating or cooling effect.
• Coils are typically manufactured from copper for the tubes, with
copper or aluminum fins to aid heat transfer.
Heating and/or cooling elements

91. • If dehumidification is required, then the cooling
coil is employed to over-cool so condensation
occurs. A heater coil placed after the cooling coil
re-heats the air to the desired supply temperature.
This has the effect of reducing the relative
humidity level of the supply air.
Dehumidifier ‫المبخـــــــر‬

92. Humidifier
• Humidification is often necessary in colder climates where continuous
heating will make the air drier, resulting in uncomfortable air quality
• Various types of humidification may be used:
• Evaporative: dry air blown over a reservoir will evaporate some of the
water. The rate of evaporation can be increased by spraying the water
onto baffles in the air stream.
• Vaporizer: steam or vapor from a boiler is blown directly into the air
stream.
• Spray mist: water is diffused either by a nozzle or other mechanical
means into fine droplets and carried by the air.
• Ultrasonic: A tray of fresh water in the airstream is excited by an
ultrasonic device forming a fog or water mist.
• Wetted medium: A fine fibrous medium in the airstream is kept moist
with fresh water from a header pipe with a series of small outlets. As the
air passes through the medium it entrains the water in fine droplets. This
type of humidifier can quickly clog if the primary air filtration is not
maintained in good order.

93. Humidifier-‫المبخـــــر‬
• Humidification is often necessary in colder climates
where continuous heating will make the air drier,
resulting in uncomfortable air quality
Various types of humidification may be used:
• Evaporative: dry air blown
over a reservoir will
evaporate some of the
water. The rate of
evaporation can be
increased by spraying the
water onto baffles in the air
………..stream.

94. Humidifier ‫المبخـــــر‬-
• Humidification is often necessary in colder
climates where continuous heating will make the
air drier, resulting in uncomfortable air quality
Various types of humidification may be used:
• Vaporizer:
steam or vapor
from a boiler is
blown directly
into the air
……….stream.

95. Humidifier ‫المبخـــــر‬-
• Humidification is often necessary in
colder climates where continuous
heating will make the air drier, resulting
in uncomfortable air quality
• Various types of humidification may be
used:
• Spray mist: water is
diffused either by a nozzle
or other mechanical means
into fine droplets and
carried by the air.
• Ultrasonic: A tray of fresh
water in the airstream is
excited by an ultrasonic
device forming a fog or
…………water mist.

96. Humidifier ‫المبخـــــر‬-
• Humidification is often necessary in colder climates
where continuous heating will make the air drier,
resulting in uncomfortable air quality
• Various types of humidification may be used:
• Wetted medium: A fine fibrous
medium in the airstream is kept
moist with fresh water from a
header pipe with a series of small
outlets. As the air passes through
the medium it entrains the water
in fine droplets. This type of
humidifier can quickly clog if the
primary air filtration is not
maintained in good order.

97. Mixing chamber
• In order to maintain indoor air quality, air handlers
commonly have provisions to allow the introduction
of outside air into, and the exhausting of air from
the building.
• In temperate climates, mixing the right amount of
cooler outside air with warmer return air can be
used to approach the desired supply air temperature.
A mixing chamber is therefore used which
has dampers controlling the ratio between the
return, outside, and exhaust air.

98. Blower/fan
• Air handlers typically employ a large blower .
• The blower may operate at a single speed, offer a
variety of set speeds, to allow a wide range of air
flow rates. Flow rate may also be controlled by inlet
vanes or outlet dampers on the fan
• Multiple blowers may be present in large
commercial air handling units, typically placed at
the end of the AHU and the beginning of the supply
ductwork .

99. Heat recovery device
• A heat recovery device heat exchanger of many types, may be fitted to
the air handler between supply and extract airstreams for energy savings
and increasing capacity. These types more commonly include for:

100. Heat recovery device
• Recuperate, or Plate Heat exchanger: A sandwich of plastic or metal
plates with interlaced air paths. Heat is transferred between airstreams
from one side of the plate to the other. The plates are typically spaced at
4 to 6mm apart. Heat recovery efficiency up to 70%.

102. Heat recovery device
• Thermal Wheel, or Rotary heat exchanger: A slowly rotating matrix of
finely corrugated metal, operating in both opposing airstreams.
• When the AHU is in heating mode, heat is absorbed as air passes
through the matrix in the exhaust airstream, during one half rotation,
and released during the second half rotation into the supply airstream.
• When the AHU is in cooling mode, heat is released as air passes
through the matrix in the exhaust airstream, during one half rotation,
and absorbed during the second half rotation into the supply airstream.
Heat recovery efficiency up to 85%.

105. • Controls
• Controls are necessary to regulate every aspect of an air handler, such as:
• flow rate of air,
• supply air temperature,
• mixed air temperature, humidity, air quality.
• Common control components include temperature sensors, humidity sensors, sail
switches, actuators, motors, and controllers.
• Vibration isolators
• The blowers in an air handler can create substantial vibration and the large area of
the duct system would transmit this noise and vibration to the occupants of the
building.
• To avoid this, vibration isolators (flexible sections) are normally inserted into the
duct immediately before and after the air handler and often also between the fan
compartment and the rest of the AHU. The rubberized canvas-like material of these
sections allows the air handler components to vibrate without transmitting this
motion to the attached ducts.

106. Overall View

107. AHU System - Disadvantages
• Long, big in size and expensive GI Duct.
• Taking extra space from the building.
• Relatively high noise levels (at high
output)
• Might have week return from far branch.
• High operating and maintenance
costs (for changing the filter and fan)

108. Full Equipped FAHU

109. By Eng. Juma Yousef Juma
jumayjuma@gmail.com +971-50-4948385